Integrated Physiology & Pathophysiology Review

Question-and-answer flashcards covering glucocorticoids, thyroid physiology, circadian rhythm, innate immunity, respiratory distress, pulmonary function tests, micturition, and renal tubular reabsorption.

What receptor do exogenous glucocorticoids bind to in target cells?

The cytoplasmic glucocorticoid receptor.

After binding its receptor, where does the glucocorticoid-receptor complex go to alter gene expression?

It enters the cell nucleus to regulate transcription.

How do glucocorticoids affect anti-inflammatory and pro-inflammatory protein synthesis?

They increase anti-inflammatory proteins and decrease pro-inflammatory proteins.

Which axis is suppressed by exogenous glucocorticoids?

The hypothalamic-pituitary-adrenal (HPA) axis (CRH and ACTH).

Name two key enzymes or mediators inhibited by glucocorticoids that reduce inflammation.

Phospholipase A2 (↓ prostaglandins & leukotrienes) and pro-inflammatory cytokines.

How do glucocorticoids affect circulating neutrophil count?

They increase circulating neutrophils through demargination.

What are two major metabolic effects of glucocorticoids?

↑ Gluconeogenesis (raises blood glucose) and protein catabolism with fat redistribution.

List three long-term musculoskeletal consequences of glucocorticoid therapy.

Muscle wasting, osteoporosis, and decreased calcium absorption.

Which cardiovascular effect is enhanced by glucocorticoids?

Vasoconstriction and blood pressure increase via potentiation of catecholamines.

Give three clinical uses of systemic glucocorticoids.

Autoimmune disease control, transplant rejection prevention, and adrenal insufficiency replacement.

Which thyroid hormone is considered the active form?

T3 (triiodothyronine).

Where is T4 converted to T3 in the body?

In peripheral tissues (e.g., liver, kidney).

What hormone does the hypothalamus secrete to stimulate thyroid function?

TRH (thyrotropin-releasing hormone).

High circulating T3/T4 has what effect on TRH and TSH?

It inhibits (negative feedback) both TRH and TSH secretion.

In primary hypothyroidism, how are TSH and T3/T4 levels affected?

TSH is elevated, T3/T4 are low.

Name the most common autoimmune cause of hypothyroidism.

Hashimoto’s thyroiditis.

Which autoimmune disorder is the most common cause of hyperthyroidism?

Graves’ disease.

What are TSH and T3/T4 levels in secondary hyperthyroidism?

Both TSH and T3/T4 are elevated.

Which hypothalamic nucleus acts as the master circadian clock?

The suprachiasmatic nucleus (SCN).

During what time of day does cortisol peak in a healthy circadian rhythm?

Shortly after waking (cortisol awakening response).

Which hormone begins to rise shortly after sunset to promote sleep?

Melatonin.

When does growth hormone (GH) reach its highest secretion during 24 hours?

During deep sleep at night.

What innate immune cells are the first responders to bacterial infection?

Neutrophils.

Which phagocytic cell type is the primary antigen presenter to T cells in skin and mucosa?

Dendritic cells.

Define chemotaxis in phagocytosis.

Movement of phagocytes toward infection sites in response to chemical signals.

What structure forms when a phagocyte completely engulfs a pathogen?

A phagosome.

What is formed by fusion of a phagosome with a lysosome?

A phagolysosome.

Which surfactant-producing lung cells are deficient in neonatal respiratory distress syndrome?

Type II alveolar cells.

What is the principal pathophysiologic feature of adult ARDS regarding alveolar fluid?

Increased alveolar-capillary permeability leading to non-cardiogenic pulmonary edema.

In obstructive lung disease, how is FEV1/FVC ratio affected?

It is decreased (<70%).

Which lung volume is typically reduced in restrictive disease but may be normal or high in obstructive disease?

Total Lung Capacity (TLC).

What pulmonary test measures the transfer of carbon monoxide across the alveolar membrane?

DLCO (Diffusing Capacity of the Lung for CO).

Which nervous system division maintains bladder storage, and what is its spinal level?

Sympathetic nervous system (T11–L2).

During bladder filling, what is the state of the detrusor muscle and internal sphincter?

Detrusor relaxed, internal sphincter contracted.

Which spinal segments supply parasympathetic fibers for bladder emptying?

S2–S4.

Which nerve provides voluntary control over the external urethral sphincter?

Pudendal nerve.

Approximately what bladder volume triggers stretch receptors to initiate the voiding reflex?

300–500 mL.

What percentage of filtered Na⁺ and water is reabsorbed in the proximal convoluted tubule (PCT)?

About 65–70%.

Which transporter on the basolateral membrane drives most solute reabsorption in the PCT?

Na⁺/K⁺-ATPase pump.

Why is early DCT fluid hypotonic relative to plasma?

Because Na⁺ and Cl⁻ are reabsorbed without accompanying water.

Which hormone up-regulates Na⁺ reabsorption and K⁺ secretion in the late DCT and collecting duct?

Aldosterone.

How does antidiuretic hormone (ADH) increase water reabsorption in collecting ducts?

By inserting aquaporin-2 channels into the apical membrane.

What is a hallmark clinical problem in ARDS leading to poor oxygenation despite supplemental O₂?

Refractory hypoxemia.

What lung test parameter is usually normal or increased in asthma but reduced in pulmonary fibrosis?

FEV1 may be reduced in asthma but TLC is often normal or high; TLC is reduced in fibrosis (restrictive).

Which circadian phase is typically best for physical performance?

Afternoon, when body temperature and alertness peak.

What mood-related side effects can high-dose glucocorticoids cause?

Euphoria, insomnia, mood swings, or psychosis.

Name two autoimmune diseases commonly treated with systemic glucocorticoids.

Systemic lupus erythematosus (SLE) and rheumatoid arthritis.

What electrolyte disturbance can chronic glucocorticoid therapy aggravate through bone loss?

Hypocalcemia due to decreased intestinal calcium absorption.